#include <STC89C5xRC.H>

void Delay(unsigned int xms)    //@12.000MHz
{
    unsigned char data i, j;

    while(xms--){
        i = 2;
        j = 239;
        do
        {
            while (--j);
        } while (--i);
    }
}
void main(){
	while(1){
		P2 = 0xF0;
		Delay(500);
		P2 = 0xFF;
		Delay(500);
}
}